In a gas turbine, a fluid, generally air and therefore designated in the following broadly as combustion air, is initially compressed to a higher pressure level and burned as a combustion air/fuel mixture in a combustion chamber before enthalpy of the exhaust gas is converted into mechanical energy in a turbine and made available as useful power.
In so doing, the combustion chamber undergoes high compressive loading and high temperature loading due to the pressure level and the combustion. Therefore, it was common in the prior art heretofore to strengthen the housing of the combustion chamber by means of inner and/or outer stiffening ribs, to use high-temperature materials, and to provide a flame tube in the housing which limits the combustion zone and thus shields the housing at least partially against the combustion heat.
Besides ceramic temperature protection layers and film cooling, impingement cooling of the flame tube is known, for example, from WO 2008/028621 A1. A perforated plate surrounding the flame tube is provided for this purpose. Compressed combustion air impinges on the flame tube from the outside through apertures in the perforated plate and cools the flame tube before being fed through a radial swirler to the interior of the flame tube and combustion chamber and burned therein.
U.S. Pat. No. 6,134,877 discloses a gas turbine combustion chamber having a housing, a flame tube received therein, and a conically shaped cylinder which surrounds the flame tube and which has openings in a downstream area for impingement cooling of a flame tube region of decreasing diameter and which is fastened at an end face to the housing. An axial flexibility of the cylinder is introduced by means of a convoluted region to enable thermal expansions. The other end of the cylinder opens into the turbine outlet.
Particularly in stationary gas turbines having freestanding combustion chambers on the radially outer side, as is shown in FIG. 1, the additional weight of the stiffening ribs 110 shown in FIG. 1 poses a problem because it impedes handling of the separate combustion chambers and loads their connection to the housing of the turbine with torque that must be supported.
Therefore, it is an object of the present invention to improve a gas turbine and the combustion chambers thereof.